So, although my main plan w/my Firebird is to focus more of my efforts towards getting it fixed up for now (mostly cosmetic stuff), and saving up for some kind of engine/trans swap down the road for more performance, I still cant help but be curious about any cheap tricks I might be able to try to get a little more power out of the 305 TBI in it now.

I've done a bit of basic reading up on the matter, but I've heard of people converting their TBI setups to TPI for more power. The questions I have are, how much does it cost to do this? is it worth the expense/hassle? and are the L03 and LB9 the same/similar internally, other than the fuel intake system? Also, how much of a power gain would be achieved by doing this? (similar to LB9 numbers?) Thanks for all and any help!

 

im not sure but im allready working on switching out my tbi for tpi and i think i'll get 30 hp from it and if i get headers i should get another 20 from thatn and another 10 from the tpi and then other lil thinks like air foils and cold air intake you could get 300 + hp out of a 305

 

WHAT?

 

you dont think so ?

 

Most guys with L98's and full exhaust don't dyno 300 at the crank. That's about 240 at the wheels, and L98's make 245 at the crank, according to stock specs.
Don't hope for too much, because it might not make that much of a difference on your 305.

Because I did a fully ported TPIS Baseplate, Fully ported and siamesed plenum and SLP Runners, Air Foil, Cold Air Intake, Headers, 2 1/2" ypipe, no cat, 3" exhaust. And my GTA isn't significantly faster, i'd say it's a candidate for a 13.8 on the strip. And that is no lie. And when i'm done with my suspension mods i'd say a good 13.7.

 

This has been covered many times.TRY searching tbi to tpi swap,or it may be in a stickie on tbi board.I think i remember seing a thread where a guy did the swap and dynoed it before and after.He showed a 20 hp increase from the intake swap alone.One thing to mention is once you replace the tbi heads and cam tpi really doesnt have much of an advantage.
Your engine made 170 hp when new,which is the same as the tbi 4.3 v6 in my 1500 4x4.Its a long way from seeing 300 hp.Yes the intake swap will put you in LB9 territory,but its a fairly involved swap.You will need to redo the fuel system with new pump and lines,complete tpi setup with all the injectors,sensors and wiring.
Do some more research on here by reading stickies and tech articles on the home page,and search the forums.


I think he would tell a difference.With a well tuned good running engine you should be better than that. know of guys on here with stock head and cam L98s that have dipped in the 12`s.My car is in mid 13s with the stock tpi,mild cam and slightly better heads.Sticky tires and stall help alot.Im hoping to see very low 13`s when i get my intake swap/tune finished and to the track.Did you have your prom reprogrammed for your intake?

 

Ya my car ran stock 13.9, but to me she doesn't seem much quicker. But I didn't want to get cocky, but I feel she's a 13.5 easy, then with drags she'd be low to mid 13s. I can't wait to run her again this year.
And no if youre changing your intake you don't need the "memcal" to be tuned.
However I did upgrade my injectors and changed the fan on temp.
I did get a custom tune by Scott Hansen.